Effect of magnetic field orientation on high gradient magnetic separation performance

The magnet has a dominant role in a high gradient magnetic separator; it provides the passage for the magnetic field and the working space where the matrix is placed to produce magnetic gradients and magnetic forces high enough to capture magnetic particles from the slurry. The effect of the magnetic field orientation of the magnet on high gradient magnetic separation (HGMS) performance has been comparatively investigated on a pilot pulsating HGMS separator with vertical and horizontal magnets respectively. The results of the investigation indicate that the magnetic field orientation has a significant effect on the performance. It was concluded that a properly designed magnet in a HGMS separator greatly improves the performance.     

Study on capture radius and efficiency of fine weakly magnetic minerals in high gradient magnetic field

The recovery of ultrafine weakly magnetic minerals using HGMS is proved a tough issue in industrial practice. Optimization of HGMS parameters determines the recovery result. The capture limits of weakly magnetic particles of diameter range 1–30 μm in high gradient magnetic field are studied using a numerical computation method. The matrix size and slurry velocity as well as the magnetic induction show great influence on the capture radius. The capture radius decreases rapidly with the decrease of particle size, the increase of matrices diameter and slurry velocity. For generalized condition, the capture radius is largely dependent on the ratio of slurry velocity V₀ to the so called magnetic velocity V_m. The capture efficiency decreases with the increase of the matrices arrangement value of d/a (the ratio of half the spacing between matrices to the matrix radius). The relationship between capture efficiency and V₀/V_m as well as d/a is obtained. This relationship can provide a guidance of choosing matrices of the perfect size and arrangements or configuring the HGMS system to work with high capture efficiency. It is also demonstrated how to regulate the HGMS system from a working point of low capture efficiency to a working point of high capture efficiency.     

基于PFC 2D高梯度磁场下煤粉干式磁选行为模拟

为了清晰认识煤粉磁选行为的特性,选取矩形磁钢-锥形聚磁介质闭合磁系提供高梯度磁场环境,建立了煤粉干式磁选过程磁性颗粒动力学模型。基于二维离散元软件PFC 2D,研究了干式磁分离过程磁性颗粒运动行为,考察了磁场强度、极距、比磁化率、锥角对颗粒运动轨迹中位移、速度、平均不平衡力的影响。结果表明：磁场强度、比磁化率越大,颗粒在磁场中受力越大,位移、速度变化越明显,有益于颗粒的磁力捕集;保持颗粒距锥尖相对距离l/2,极距越小,位移、速度变化趋势越大,越有利于磁性颗粒的吸附、系统的稳定;锥角为π3时,颗粒所受磁场力最大,系统易达到平衡状态;锥角对系统影响最弱,比磁化率较极距、磁场强度对系统影响大。     

A Stokesian dynamics approach for simulation of magnetic particle suspensions

The dynamic behaviour of μm-scale ferromagnetic particles in suspension is of interest for various mineral beneficiation processes. It is, however, difficult to experimentally study such processes at the particle-level. In these instances it can be advantageous to resort to suitable particle simulation methods.Stokesian dynamics is a mesh-free numerical technique developed for suspensions of nm to mm size particles. The method inherently considers hydrodynamic interactions, but additional interaction models can be included depending on the system under investigation. We here present a Stokesian dynamics (SD) implementation, which allows for simulation of the motion of suspended magnetic particles in presence of an external magnetic field. The magnetic interaction model includes particle-field interactions as well as pairwise interactions between magnetised particles.Simulations are compared with experiments using a laboratory-scale flow cell. The method is shown to be realistic for studying ferromagnetic suspensions in mineral processing applications, and can be useful in understanding and predicting the efficiency of mineral separation processes.     

强磁选机的技术进展

介绍了湿式强磁选机优化结构、提高场强，以及改进永磁强磁选机性能方面的技术进展。     

棒介质层数对高梯度磁选指标的影响

棒介质作为高梯度磁选的一种分选介质,广泛应用于氧化铁矿、钛铁矿、黑钨矿等弱磁性金属矿的选矿和高岭土、石英、长石等非金属矿的除铁提纯。棒介质作为分选过程的载体,其结构构造(如排列、丝径、丝距、层数等)对棒介质堆内部的磁场特性和磁性矿粒动力学具有决定性影响,从而显著地影响高梯度磁选的效能。运用"单元介质"分析法,进行棒介质脉动高梯度磁选微细粒赤铁矿试验,分别研究2 mm和3 mm棒介质的介质丝层数对高梯度磁选指标的影响。试验结果表明,对每种层数的棒介质,随着磁感应强度上升,介质丝对磁性矿物的捕获能力增强,精矿产率和铁回收率增大,而精矿和尾矿品位下降,分选效率规律不明显;随棒介质层数的增加,高梯度磁选指标则明显提高。     

强化高梯度磁选分离细粒黄铜矿和辉钼矿的研究

黄铜矿和辉钼矿存在磁性差异,因此理论上两者可以采用高梯度磁选分离,并且物料粒度和粒度分布是影响高梯度磁选铜钼分离效果的重要因素。本研究分析了磁介质捕获不同细度黄铜矿的特性,开展了脉动高梯度磁选分离不同粒度黄铜矿-辉钼矿纯矿物混合矿试验,并对比研究了实际铜钼混合精矿分级后和全粒级入选的脉动高梯度磁选效果。研究表明：脉动高梯度磁选对细粒黄铜的回收效果较差,且细粒辉钼矿在磁力捕获产品中的机械夹杂明显比粗粒辉钼矿更严重。铜钼混合精矿分级后的脉动高梯度磁选铜钼分离效果,明显优于全粒级铜钼混合精矿入选的铜钼分离效果。将铜钼混合精矿分级成+0.025 mm和-0.025 mm两个粒级后,在最佳条件下开展脉动高梯度磁选试验,获得的铜精矿铜回收率为55.36%,Cu和Mo品位分别为30.86%和0.067%,钼精矿Mo回收率为91.72%。该研究结果可以用于指导脉动高梯度磁选分离铜钼的工业应用。     

棒介质排列组合对高梯度磁选指标的影响研究

脉动高梯度磁选是微细粒弱磁性矿物的高效选矿技术,通过用微细粒赤铁矿进行脉动高梯度磁选试验,研究棒介质排列组合对高梯度磁选指标的影响。试验发现,棒介质排列组合对高梯度磁选指标具有明显影响,交叉排列优于矩形排列,可以获得更高的精矿品位、铁回收率和分选效率;随介质丝间距的增大和介质丝层数的减小,介质丝对磁性矿物的捕获能力降低,导致尾矿铁品位上升,分选效率下降,而精矿品位变化不明显。可以得出结论,棒介质排列组合优化,可以明显提升高梯度磁选的效能。     

立环脉动高梯度磁选机在梅山铁矿的应用

介绍了ＳＬＯＮ－１５００立环脉动高梯度磁选机的工业试验和应用情况,总结了该设备的优点及存在的问题。     

锌硫分离尾矿回收锡的磁选试验研究

针对某锡多金属硫化矿锌硫分离尾矿锡损失率较高的问题,对锌硫分离尾矿进行回收锡试验研究。通过方案对比,确定了采用简单的磁选方案脱除尾矿中磁黄铁矿和黄铁矿,可达到富集锡的目的。实验室试验可获得锡品位1.65%、锡作业回收率63.10%的锡精矿;该工艺成功实现了工业化应用,工业生产上可获得锡金属富集比为1.39和对原矿回收率4.94%的锡精矿,经济效益显著。     

HMDC高强磁选机的研制

应用计算电磁学及电磁仿真技术确定了高强磁极组参数和辅助反斥磁极组参数,并在此基础上对HMDC高强磁选机进行了设计。阐述了HMDC高强磁选机的工作原理和技术特点及其在选煤厂加重质回收和净化系统的应用情况。实践表明,该磁选机磁性物回收水平高、应用前景广阔。     

高梯度磁选微细粒赤铁矿尾矿的棒介质筛选

在赤铁矿、褐铁矿等弱磁性铁矿石的加工过程中会产生大量的-20μm微细粒级尾矿,目前该粒级弱磁性矿物的回收率低。对-20μm粒级65%、铁品位为28.99%的某微细粒赤铁矿尾矿,进行脉动高梯度磁选的棒介质直径筛选试验研究,了解棒介质丝径对分选指标的影响。结果表明,在磁感应强度为0.5T的条件下,1mm丝径棒介质可以获得品位为46.85%和回收率为59.39%的铁精矿,该指标明显优于当前应用的2mm和3mm棒介质。     

Using an axial electromagnetic field to improve the separation density of a dense medium cyclone

To produce an on-line control method to improve the separation density of a given suspension density of a dense medium cyclone, a thin solenoid coil was placed in the cylindrical part of a cyclone. The dense medium distribution test and −3 + 0.125-mm coarse slime separation tests for different electric currents were performed. Float-and-sink analysis was performed for the separation products. The magnetic force of the particles under a magnetic field was also simulated. The results indicated that the presence of a magnetic field can improve the separation density by increasing the “separation cone density” caused by the inward radial motion and the upward axial motion of the magnetic particles. This approach provided a new separation density manipulation method for dense medium cyclones via application of a magnetic field.     

SLon高梯度磁选机在国外某进口铁矿石的研究与应用

国外某进口铁矿TFe含量49.11%,工艺矿物学研究发现块状赤铁矿中包裹粒状磁铁矿、褐铁矿交代共生,呈脉状、网状穿插嵌布于脉石矿物中,部分赤铁矿和褐铁矿嵌布粒度过细,难以解离,影响磁选铁精矿中铁的品位和回收率。通过条件试验确定该矿物磁选条件为在弱磁选磁场强度1 000 Gs下、强磁粗选和扫选场强分别采用7 000 Gs和11 000 Gs、强磁选机脉动冲次采用210 r/min。在条件试验基础上进行了连续扩大半工业试验,弱磁选机采用SCT-44永磁磁选机、强磁选机采用SLon-500立环脉动高梯度磁选机,可获得综合精矿铁品位63.24%、铁回收率93.67%的良好指标,为国内进口铁矿采用SLon高梯度磁选机磁选回收利用提供了参考及试验依据。     

外加磁场与表面活性剂对水表面张力影响程度对比

为了增强井下防尘管路中水的润湿性,利用磁化仪和高斯计对不同水样进行了磁处理,研究分析了不同场强及磁化时间下外加磁场对水样表面张力的影响程度及特征,并与表面活性剂的试验情况进行了比较.结果表明:一定磁场参数下,外加磁场能够降低水的表面张力,但对其影响程度相对较小.具有较高初始表面张力的水样被磁处理后,平均表面张力一般为50 ～ 60 mN/m,降低了7.2％ ～27.1％,且随磁场参数的改变有一定的波动;而使用表面活性剂在较低浓度下就可使水的表面张力降低至50 mN/m以下,最佳表面活性剂可使其进一步降低至30 ～ 40 mN/m,降低幅度可为外加磁场的1.5 ～4.0倍以上.外加磁场可以作为一种改变水润湿性的绿色方法,但应根据现场具体条件及需求,并结合磁化水其他特性的研究进行选择应用.     

赣州某萤石尾矿浮选柱分选实验研究

这是一篇矿物加工工程领域的论文。云锡集团卡房分公司新探获矿体除有价元素铜、钨以外,仍有价值不容小视的萤石资源。铜钨浮选尾矿中CaF₂品位高达31.98%,萤石矿物整体属粗中粒嵌布,单体解离度在95%以上,脉石矿物以钙铁辉石、石英、长石为主。选矿小型实验首先采用强磁选预选脱除了钙铁辉石等磁性脉石矿物,减少了对萤石浮选的干扰,然后采用“一粗两扫六精”的浮选工艺,选择酸化水玻璃做调整剂,选择油酸钠做捕收剂,对中矿产率较大的精选1中矿返回至扫选1作业,最终获得了CaF₂品位为96.27%、回收率为88.85%的萤石精矿产品,实现了卡房矿区萤石资源的高效综合利用。     

电磁场对重介质旋流器分选密度的影响

为研究重介质旋流器外部电磁场的磁场位置、强度对其分选密度的影响,以磁铁矿粉为介质,将重介质旋流器置于同轴的螺线圈磁场中进行试验。试验结果表明:当磁场位于重介质旋流器柱体上端时,低磁场强度可提高其分选密度;当磁场位于重介质旋流器锥体下端时,高磁场强度可降低其分选密度。通过对重介质旋流器外部电磁场位置和强度的调节,可以达到调节其分选密度的目的,为实现其二段分选密度的在线调控提供一定的理论支持。     

高压电选机内电晕电流和电场的分布规律

在电选过程中，分选带较短，物料参选时间短，在这很短的时间内完成荷电、放电、最终分离，分选带内滚筒表面附近的电晕电流和电场分布情况就起着直接的决定作用。对电选机内电晕电流和电场分布规律进行了较深入的理论和试验研究，并以此为依据，对电选实践中如何通过调节操作参数、结构参数来改善分选效果进行了分析。研究结果表明：（1）电晕电极的主要作用是产生电晕电流，同时也产生静电场；电晕电流和场强随极间电压升高或极距减小而增强；（2）电晕电流和场强沿接地滚筒表面呈正态分布；（3）静电极主要产生强静电场，静电极对电晕电极的电晕放电有屏蔽作用；（4）在分选过程中应采用高电压、大极距的操作制度和电晕－静电复合电极结构。     

The effect of breakage method on the shape properties of an iron-oxide hosted copper–gold ore

Using a mineral liberation analyser (MLA), the shape properties of an iron-oxide hosted copper–gold ore following comminution in either a hammer mill or a piston–die compression unit were examined. It was found that particle angularity distributions were able to be fitted to the beta distribution, providing a convenient way to quantify changes in particle shape properties as a function of the breakage method employed. Particles discharged from the hammer mill were less angular than particles discharged from the piston–die compression unit. This was attributed to attrition breakage mechanisms, whereby topographical features are chipped off parent particle surfaces. The results suggest that the quantification of shape properties is a convenient method for obtaining insight into the nature of breakage events that take place inside comminution devices.     

基于ANSYS的永磁除铁器的磁场计算与分析

利用ANSYS软件中的电磁场分析计算模块,对永磁除铁器的磁场分布进行计算,得出了额定吊高下的磁通密度,并通过试验验证了仿真的正确性。进而分析了不同磁轭厚度对磁场分布的影响,为永磁除铁器的设计提供依据。